Ventilation system

ABSTRACT

The present invention provides in one aspect a ventilation system for removal of foul air from a toilet bowl, where the toilet is of the flush down type having a cistern storing water for flushing the toilet bowl and with a flushing pipe feeding from the cistern to the toilet bowl for flushing the toilet bowl, the system having an air extractor fan communicating with an air extraction pipe which communicates, in turn, with the flushing pipe whereby the air extractor fan may draw foul air from the lavatory bowl via the flushing pipe and air extractor pipe and expel it through a removal pipe, wherein between the air extraction fan and the toilet bowl there is provided a baffle to deter flow of moisture on the internal walls of the overflow pipe from travelling upwardly to the extractor fan.

RELATED APPLICATIONS

This application is a continuation in part of PCT/GB2005/001361, having an international filing date of 8 Apr. 2005, and PCT/GB2006/001291, filed 4 Oct. 2006, both having designated the United States, and the disclosures of which are incorporated herein by reference.

FIELD OF THE INVENTION

The present invention concerns improvements in and relating to ventilation systems, and particularly to toilet odour ventilation systems of the type where an extractor fan is built into the toilet to extract air from in and around the toilet bowl.

BACKGROUND TO THE INVENTION

Toilet odour ventilation systems have proven a fertile ground for innovation over the last few decades with many and various proposals for fan-assisted mechanisms to extract the air from a toilet bowl. For example, GB-2126263 describes a system for ventilating water closets in which the extractor fan is connected to the toilet bowl/lavatory pan via ducting which connects to the flush downpipe from the system to the pan and draws air up from the bowl through a lower section of the flush pipe and out through the ducting to the exterior. The fan is triggered by switching a light on or by operation of a pressure switch. Other example prior systems include U.S. Pat. No. 4,583,250 and US2002/0073482.

In general many of the multifarious prior art proposals for toilet ventilation systems are no more than paper proposals that their proponents had not tested in practice. Indeed it is in fact far from simple to configure such a system to operate reliably. In contrast to predecessors, the present applicants have found through extensive trial and development work that prior proposals are generally unviable and do not enable effective removal of malodorous air and that a specific system configuration is needed to achieve reliable and economic functioning. The present invention thus seeks to provide as system that is reliable, economical, compact, efficient and versatile. The functioning of the system is suitably also more efficiently configured relative to the flushing operation of the toilet than in prior systems and is suited for retro-fit to existing toilets without extensive re-modelling.

Amongst further problems that plague such air extraction systems is the difficulty of keeping the electric motor and wiring of the fan substantially free of moisture that may otherwise eventually lead to corrosion and possible failure of the motor.

SUMMARY OF THE INVENTION

In a first aspect of the present invention, there is provided a ventilation system for removal of foul air from a toilet bowl, where the toilet is of the flush down type having a cistern storing water for flushing the toilet bowl and with a flushing pipe feeding from the cistern to the toilet bowl for flushing the toilet bowl, the system having an air extractor fan mounted within the cistern and communicating with an air extraction pipe which communicates, in turn, with the flushing pipe whereby the air extractor fan may draw foul air from the lavatory bowl via the flushing pipe and air extraction pipe and expel it through a removal pipe, wherein the air extraction pipe and at least such of the length of flushing pipe that is within and emerges through the cistern are substantially straight and the air extraction pipe is aligned with the flushing pipe and with the air extractor fan whereby air may flow directly in a straight line into and up through the flushing pipe length and the air extraction pipe into the fan for expulsion.

By adopting this in-line configuration the requisite airflow for malodorous air removal can be reliably achieved with an adequately compact and moderately low powered motor. Furthermore, the system can be adopted for toilets as a retro-fit and requires no re-modelling of the toilet. The systems clever compact design enables it to fit comfortably into even the smallest standard cistern size of 300 mm deep and with no extra pipes being needed at its lower end.

Preferably the system further has a flushing mechanism comprising a tubular sleeve that is mounted telescopically to the air extraction pipe and which when moved telescopically opens at least one aperture into the air extraction or flushing pipe for water to flow thereinto from the cistern. This configuration of flushing mechanism facilitates and enhances the compactness and efficiency of the air extraction system. Indeed, in an allied aspect of the present invention there is provided a ventilation system for removal of foul air from a toilet bowl, where the toilet is of the flush down type having a cistern storing water for flushing the toilet bowl and with a flushing pipe feeding from the cistern to the toilet bowl for flushing the toilet bowl, the system having an air extractor fan mounted within the cistern and communicating with an air extraction pipe which communicates, in turn, with the flushing pipe whereby the air extractor fan may draw foul air from the lavatory bowl via the flushing pipe and air extraction pipe and expel it through a removal pipe, wherein the system is formed or assembled with a flushing means for flushing of the toilet comprising a tubular sleeve that is mounted telescopically to the air extraction pipe and which when moved telescopically opens at least one aperture into the air extraction or flushing pipe for water to flow thereinto from the cistern.

Suitably the system further has a baffle that comprises a generally frusto-conical barrier that is annular and which preferably is mounted in the air extraction pipe in proximity to the air extraction fan to restrict back flow of any moisture from the air extraction pipe to the air extractor fan.

Preferably the air extractor fan is housed within a substantially watertight casing within the cistern. In one particularly preferred embodiment the system of the present invention is, with the exception of control circuitry, substantially wholly packaged within a cistern and which may be relatively straightforwardly coupled to an otherwise substantially conventional toilet.

Particularly preferably the flushing valve is moved to its open position by an electric motor and preferably the electric motor is housed within a substantially watertight housing that is installed within the cistern, in use, and preferably this is the same substantially watertight housing as accommodates the extractor fan. By combined housing of an electric motor operated fan with an electric motor for operating the flushing action of the toilet both within the same substantially watertight housing the arrangement is made significantly more economical and compact than would otherwise be the case. Indeed, the implementation of a ventilation system makes viable the use of an internal electric motor within the system for flushing of the cistern.

With an electric motor operated flushing mechanism, the system suitably further comprises a control panel incorporating a processor means and one or more switches to enable the user to select a flushing operation action. Suitably the processor and switch means allow the user to select between different volumes of flush.

The system is preferably provided with a processor programmed to control operation of the extractor fan for a predetermined time duration. Suitably the system has an electric sensor to sense the presence of a toilet user and to automatically activate operation of the extractor fan. This suitably comprises a proximity sensor and which preferably is incorporated into a control panel as aforementioned. Particularly preferably the system will fully automatically flush and preferably when the user is sensed to be moving or have moved away. Suitably the processor triggers operation of the extractor fan directly once the flush action has occurred.

According to a further aspect of the present invention there is provided a ventilation system for removal of foul air from a toilet bowl, where the toilet is of the flush down type having a cistern storing water for flushing the toilet bowl and with a flushing pipe feeding from the cistern to the toilet bowl for flushing the toilet bowl, the system having an electric motor driven air extractor fan mounted adjacent to, on or within the cistern and communicating with an air extraction pipe which communicates, in turn, with the flushing pipe whereby the air extractor fan may draw foul air from the lavatory bowl via the flushing pipe and air extractor pipe and expel it through a removal pipe, wherein the system is formed or assembled with a flushing means for flushing of the toilet, the flushing means having an electric motor drive and processor to control the system to automatically flush and then automatically operate the extractor fan.

Particularly preferably the electric motor drive comprises a worm gear, or threaded gear and suitably wherein the worm gear, or threaded gear, is a moulded part. Preferably the electric motor drive comprises a moulded drive nut that is driven by the worm gear, or threaded gear.

Preferably the valve sleeve has a support arm projecting therefrom and having a socket in which the drive nut is inserted in use to drive the valve sleeve.

BRIEF DESCRIPTION OF THE DRAWINGS

A preferred embodiment of the present invention will now be more particularly described, by way of example, with reference to FIGS. 17 onwards of the accompanying drawings.

FIG. 1 is an exploded general assembly diagram of a prototype ventilation system;

FIG. 2 is a perspective view corresponding to FIG. 1 and showing the primary components of the general assembly of FIG. 1 in assembled state;

FIG. 3 is a view similar to FIG. 2 and showing the system of the invention incorporated into a cistern;

FIG. 4 is a side elevation view of central components of the assembly comprising a sealed housing for the extractor fan with integral communicating air extraction pipe and flushing pipe section with associated valve closure;

FIG. 5 is a transverse sectional view through the central components of FIG. 4;

FIG. 6 is a perspective view of the valve arrangement shown in FIG. 5;

FIG. 7A is a perspective view of an alternative arrangement of lever operating mechanism for the valve; and

FIG. 7B shows the same in raised operative state;

FIGS. 8 to 13 show central components of the assembly in greater detail, with FIG. 8 being a perspective view of the central components comprising extractor fan housing and extraction pipe with the upper part of the air removal pipe and fan housing removed to show a non-return valve in the air removal pipe;

FIG. 9 is a side elevation view of the componentry of FIG. 8 and with upper part partially cut away;

FIG. 11 corresponds to FIG. 9 but with an upper part of the extractor fan housing reinstated;

FIG. 12 is an elevation view of the componentry of FIG. 11 facing on to the air removal pipe;

FIG. 13 is a longitudinal sectional view taken through the componentry of FIG. 12 along the line C-C in FIG. 12;

FIG. 14 is a perspective view of the assembly showing internal componentry;

FIG. 15 is an alternative perspective view of the same;

FIG. 16 is a front elevation view of an example control panel arrangement;

FIG. 17 is an exploded general assembly diagram of the preferred embodiment of system of the present invention;

FIG. 18 is a perspective view corresponding to FIG. 17 and showing the primary components of the general assembly of FIG. 17 in assembled state;

FIG. 19 is a schematic longitudinal sectional view through the system of FIG. 18;

FIG. 20 is a top plan view of the FIG. 18 system;

FIG. 21 is a right side elevation view of the FIG. 18 system;

FIG. 22 is a left side elevation view of the FIG. 18 system;

FIG. 23 is a front elevation view of the FIG. 18 system;

FIG. 24 is a perspective view of the modular worm gear and housing dis assermbled;

FIG. 25 is a perspective view of the modular worm gear and housing assermbled;

FIG. 26 is an exploded general assembly view of a more compact variant of fan and motor assembly housing;

FIG. 27 is a top plan view of the FIG. 26 system;

FIG. 28 is a right side elevation view of the FIG. 26 system;

FIG. 29 is a left side elevation view of the FIG. 26 system; and

FIG. 30 is a front elevation view of the FIG. 26 system.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring firstly to FIG. 1, the prototype system thereshown comprises a fan assembly 1 having an upper mounting component 2 to mount to the extractor fan housing 3. A lower part of the fan assembly 1 comprises a fan impeller 4, a central cylindrical body of which houses an electric motor to drive the fan in rotation relative to the static upper mounting part 2 of the fan assembly 1. The cylindrical body 4 provides a substantially watertight inner enclosure for the electric motor and receives an electrical supply from contacts on the static upper part 2 of the fan assembly 1.

The housing 3 of the fan assembly 1 has a separable lid section 3 a that is adapted to be screw fixed, bolted, clipped or otherwise secured to the main part of the fan housing 3 and which enables access within the housing 3 for any necessary maintenance to be carried out on the fan assembly 1 or other components within the housing 3. Screws or bolts of aluminium are particularly preferred as a preventive measure against corrosion.

The housing 3 and suitably all primary body components of the extractor and flushing assembly are moulded of plastics, including the fan assembly 1 since, as will be appreciated from FIG. 3, the whole assembly, including or excluding control circuitry, is to be accommodated within a toilet cistern and much of it substantially permanently at least partly immersed within the body of water in the toilet cistern.

The lid section 3 a of the extractor fan housing 3 is sealed to the main part of the extractor fan housing 3 in a fluid-tight manner with an elastomeric sealing gasket 5 that is fitted into the upper rim of the main part of the extractor fan housing 3 and onto which the lid section 3 a seats. Alternatively the gasket may be dispensed with provided that the two parts are fastened together tightly and securely.

The main part of the extractor fan housing 3 is not an isolated component but rather is a moulding that is integral with an elongate pipe section that extends downwardly in use and which functions as an air extraction pipe 6. The pipe section/air extraction pipe 6, furthermore, has at its lower end an integrally moulded or assembled extension section 7 that defines an upper part of a manifold chamber 8 extending to one side of the air extraction pipe 6. The chamber 8 serves in the manner of a manifold that not only provides fluid communication between the extraction pipe 6 and a flushing pipe section length 9 a but also communicates with a valve closeable opening 10 that is provided in the upper section 7 of the chamber 8 and which admits flushing water when a flushing valve 11 is opened.

The flushing valve element 11 is a plug-like moulding with a frusto-conical tip 12 that is adapted to be guided and seat reliably into the central guide aperture 13 of an annular seat member 14 for the valve. The annular seat member 14 has a configuration resembling the plug seat of a basin and is itself firmly seated and glued or cemented into the aperture 10 of the upper housing member 7.

The flushing valve 11 is suitably formed as a two-shot moulding with the core being moulded in polypropylene or other hard plastics material and the outer being moulded in a soft elastomeric material such as natural rubber. The rubber outer is moulded around the core so that the two materials integrate directly with each other and bond securely.

The plug-shaped flushing valve 11 is mounted adjacent to and substantially parallel with the axis of the air extraction pipe 6 to provide a compact configuration and facilitating operation of the valve 11 by an electric motor 15 that is mounted in a lateral bulge 16 of the extractor fan housing 3. The electric motor is suitably a stepping motor but could comprise a solenoid or servo motor (indeed, in alternative embodiments of the first aspect of the present invention, the motor 14 might not be used and instead the valve 11 be operated by a substantially conventional manually operated lever arrangement).

The stepper motor 15 is entirely encased within the housing 3 but with its drive shaft 17 protruding through the housing 3 to operatively engage with a lever member 18 whereby the lever member 18 may be rotated through an arc of movement that raises or lowers a link member 19 that is suitably a rigid rod and which is pivotally connected at one end to the lever member 18 and at the other end to the valve 11. In an alternative version of lever member 18 and link member 19, a cam-shaped lever member 18′ may be used as is illustrated in FIGS. 7A and 7B and which has a substantially arcuate cam surface and wherein the link member 19 is not a rigid rod but rather is a chain or moulded strap or similar inelastic flexible member that is raised or lowered by movement of the lever member 17′ through an arc. Such an arrangement has the benefit of keeping the link member 19′ substantially aligned with the axis of the plug-shaped valve 11 and seat 14 to ensure a smooth seating and unseating action.

The housing of the motor 17 suitably is in some degree of air communication with the fan whereby the fan's operation assists in blowing air through the motor housing to prevent condensation build-up.

In keeping with the design of the ventilation assembly to be compact and economical in construction, it suitably further incorporates, as illustrated, an overflow pipe arrangement that feeds directly into the air extraction pipe 6 or associated moulding components 7, 9 such that should the level of water in the cistern exceed a maximum limit it will allow water from the cistern to flow down through the overflow pipe and communicating with the flushing pipe to deliver the overflowing water into the toilet bowl.

The overflow pipe arrangement illustrated comprises a short tubular section 6 a at the lower end of the air extraction pipe 6 that extends laterally from the air extraction pipe 6 and has coupled to it an elbow joint 22 that is suitably of conventional stock for plumbing. This elbow joint 22 is in turn connected to an upper pipe section 23 of the overflow and at the uppermost end of the upper pipe section 23 is a floating ball 24 that is held captive within a cage moulding 25 and which as the water level rises in the cistern is able to float upwardly with the rising water sufficiently to open up the upper end of the upper pipe section 23 for the overflowing of water down through the pipe section 23 and ultimately down through the flushing pipe section 9 a.

With respect to the flushing pipe 9 a of the assembly, this is shown as a short externally screw-threaded pipe section that is adapted to be mounted to an existing flushing pipe of a toilet. For the purposes of the invention as claimed, the flushing pipe as claimed may be wholly comprised of an existing toilet flushing pipe or channel to which the cistern and ventilation assembly are coupled.

Operation of the ventilation system is controlled by a control panel 27 with an in-built processor and which suitably also has a proximity sensor and is provided with a number of manually operable switches to adjust settings of the system, including adjustment of volume of flush between, for example, half flush and full flush.

Suitably the processor in the control panel 27 is also programmed to allow the user to select between modes or levels of operation of the ventilation. In a particularly useful embodiment of the invention, the operation of the ventilation may be selected to run continuously, suitably at a preselected percentage of the full power level so as to serve as part of a general ventilation/air conditioning component of the building in which it is installed. Thus, the ventilation will not be solely for the purpose of removing odours from the toilet but also as part of the system for refreshing air within a room or a building on an on-going basis. Where this facility is provided, the user needs to have the ability to switch between the use of the facility or switching it off and using the system essentially only for ventilating at or around the time when the toilet is in use (suitably for a preset or user selectable duration of several minutes).

With reference to FIG. 16 which shows an example control panel layout, the second button of the set of six buttons along the top of the control panel is labelled “CRU” to signify cruise control, i.e. continuous operation of ventilation. Conversely, when the “AUTO” button is selected, the system will operate to a pre-set percentage of full power only once a user is detected. The illustrated control panel 27 has a proximity sensor 28. However, alternative types of sensor may be used and suitably there is a sensor facility 28′ in association with the toilet cistern itself, suitably on a switch module 26 mounted to the system and that provides control over the level of flush in a location on the cistern that is more familiar to a user.

Regardless of the control setting of the ventilation, where the electric flush facility is provided this does, of course, need to be continuously available to the user regardless of the status of the ventilation system and suitably the processor is programmed to enable calibration for set up allowing, amongst other parameters, for adjustment of the amount of time the flushing device needs to be operated to give a full flush, such that a half flush can be delivered. For settability of the control processor, a security code accessed program is suitably provided so that adjustments can be made, for example on installation of the system, in a way that can exclude tampering by unauthorised persons.

In a yet further refinement to the system that is of particular interest to health authorities amongst others, the “intelligent toilet” of the present invention may be further configured not only to flush under electronic control and ventilate under electronic control but also to sense and weigh an individual seated upon the toilet. Weight sensors may be positioned in a toilet seat and communicate with the control processor in the control panel 27 to enable the weight of a user of the toilet to be measured and to be displayed on a display screen of the control panel 27.

Further refined features of the system may include a microphone and speaker built into the fascia of the control panel 27, with the speaker being able to relay various preset audible messages to the user or operator.

In normal operation of the system, when a user approaches or sits upon the toilet seat this suitably automatically triggers operation of the ventilation system, when it is in its reactive mode of operation. The triggering of the system will lead to activation of the electric motor of the extractor fan which as the impeller 4 of the fan rotates will draw air up through the flushing pipework of the toilet, up through flushing pipe section 9 a of the manifold chamber 8, up through air extraction pipe 6, through the impeller 4 and expelling the air out through air removal pipe 20 suitably to the exterior of the toilet cubicle and to the outside atmosphere. The air is removed via air removal pipe 20 that incorporates a non-return valve 21 which is illustrated as comprising a gate flap 21 that is hinged to flap open to allow outflow of air but prevent return flow. When the user is ready to flush the toilet he simply activates flush, selecting the desired flush operation either on the local switch module 26 on the cistern or at the remote control panel 27. Activation of flush activates the partial rotation of the stepper motor 15 causing the lever 18 to move in an arcuate movement and hence raising the link member 19 and the attached flushing valve 11 to allow water to flow through the aperture 10 and down through the manifold 8 and out through the flushing channel 9 a. This flushing operation may be executed simultaneously with the ongoing operation of the extractor fan assembly 1.

Importantly, the motor and power feeds for the extractor fan 1 are protected as far as possible not only by the moulding and substantially water-tight construction of the fan assembly 1 but also by the provision of a frusto-conical barrier wall 30 at the throat of the air extraction pipe 6 where it meets the fan assembly housing 3 (see FIG. 10). This frusto-conical barrier wall 30 helps to prevent any flow of moisture clinging to the inner walls of the air extraction pipe 6 from passing upwardly toward the air extractor fan 4 under the suction from the fan. By this measure the maintenance intervals for maintenance or replacement of the air extractor fan are considerably enhanced and whereby the system as a whole becomes significantly more commercially viable.

Turning now to FIGS. 17 to 25, these illustrate the preferred embodiment of the invention. This is far more reliable and more efficient at thorough flushing than the prototype and is compact and relatively simple to install. Here like features are given like reference numerals to the prototype. The primary differences lie in the nature of the flushing valve arrangement and the provision of the control processor housed in or proximate the fan housing of the system and thus to be installed within the toilet cistern as a substantially complete unit with substantially only the proximity sensors/switches and any displays mounted outside of the cistern.

The PCB of the control processor 42 that controls the fan actuation and speed and the motor for the flush mechanism is here shown as encased in an annexe housing 41 that is bolted or otherwise fastened onto the top of the fan housing 3 a′. A 9V battery is housed in the compartment with the PCB of the control processor 42.

A separate housing, not shown, fits onto the top of the cistern (utilizing the top hole in the cover) or is wall-mounted for built-in cisterns and houses two proximity sensors (long and short range) and two led's together on a further PCB. Both PCB's are coated to withstand moisture. The control PCB has a control that enables the installer to adjust the speed of the fan.

The sensor PCB's two levels of user proximity sensor comprise one with a range of suitably approx 750 mm and which faces forwardly in use to detect a person and turn on the fan if the sensor is stimulated for eg 5 seconds. The other sensor is short range ( eg 150 mm) and faces sideways or upwards depending on the installation requirements.

The forward facing sensor housing suitably has two leds, one green (for short flush) and one red (for long flush) or both leds are the same colour and two come on for the long flush and one for the short flush. This would be preferable for bad lighting situations or colour-blind users. The single led is activated once the fan starts, showing that the short flush (default) option is operating.

After the user has finished, he or she places their hand over the side or top firing sensor. If the sensor detects a “wave” (i.e. broken pulse) it flushes the toilet on the short flush. If the user holds their hand stationary in front of the short range sensor for eg 3 seconds the software adjusts the flush to Long Flush. The user can see this by the fact that two leds are lit rather than one. If the user walks away without flushing the toilet, the long range sensor, after eg 10 seconds, automatically flushes the toilet on the default setting (short flush). After the toilet flushes in either mode the fan runs on for another eg 20 seconds. If a user wants to flush the toilet for any reason they can do so by ‘waving’ their hand over the short range sensor.

A full flush is defined by the complete opening of the cistern valve and a dwell time of eg 2 seconds for water evacuation before closing. This means that the motor runs one way, stops and then reverses. A short flush is defined by the motor running for a short period of time (maybe only 1 second), stopping and then reversing immediately. In both long and short flush the motor is suitably turned off by the rising current it draws as the valve reaches its extreme operating positions.

In this embodiment the motor 17′ is preferably not a stepper motor but suitably a DC motor that is geared to drive the valve. The motor 17 drives a worm gear 31 to operate the valve. The worm gear 31 is suitably formed as a plastics moulding suitably comprising acetal and co-operates with a drive nut 37 that suitably is also a plastics moulding (and particularly preferably comprises nylon suitably alone or in combination with acetal) to move the valve.

It will be seen that, unlike the prototype, here the valve is configured telescopically and, indeed, substantially concentrically with the air extraction pipe rather than alongside it. The air extraction pipe comprises upper 32 and lower 33 pipe lengths that are ensheathed in an external sleeve 35, which sleeve serves as the valve. The sleeve 35 is able to move telescopically up and down relative to the air extraction pipe 32,33 and has at its lower end an annular flange arrangement 38, which carries an annular sealing washer 39. The rubber/elastomeric sealing washer 39 is configured to seat against a very smooth or highly polished annular lip 43 that projects. upwardly from the base part 40, 9 a of the system that mounts the assembly to the cistern and/or serves as a manifold and will, when raised away from contact with this lip/seat 43 by the raising of sleeve 35 by the worm drive 31,37, allow water from the cistern to flush into the lower part 33 of the air extraction pipe via the lateral (radial) apertures 34 therein and thence out down the flushing pipe length 9 a into the toilet bowl.

The interaction of the motorised worm drive, sleeve, washer and seat provides a highly efficient and effective control of flushing and substantially prevents seepage.

When the elastomeric sealing washer 39 pushes against its seat, annular lip 33, the sensed load (current draw) on the motor 17′ will exceed a threshold whereupon the processor will stop the motor 17′. This ensures that every flush cycle is separate and no out of sync build up can occur. In addition to or alternative to such feedback control of the motor 17′ its extremities of driving movement may be determined in response to sensors sensing the time duration of movement at a known rate or directly/proximity sensing when the motor, drive, sleeve or washer reach required extremity positions.

The arrangement of the washer 39 relative to the seat/lip 33 is suitably such that the seal is maintained by the water pressure in the cistern and is easily broken on driving the valve sleeve 35 upwardly.

As with the first embodiment there is provision for overflow via overflow pipe 23 down through coupling pipe section 44 through an aperture 45 into the flushing pipe section length 9 a. The air extraction pipe upper length 32 is also provided with the internal moisture baffle 30′ to deter moisture from travelling back to the fan 1.

Referring now to FIGS. 24 and 25, these show a refinement to the apparatus wherein the drive nut 37 that engages with the drive gear/worm gear 31 is formed as a separate injection moulded insert 37 a, suitably of acetal or nylon/acetal, that fits tightly into/clips into an integral socket on the radially projecting cantilevered support arm 36 that is integrally moulded with the sleeve 35 and mounts the drive nut 37 to the sleeve 35. The drive nut 37 slides into the socket transversely/perpendicularly relative to the axis of motion of the sleeve 35 and is held securely in that axial direction. This modular/cartridge style construction facilitates cost economy in manufacture of the sleeve and nut, enhancing stability and longevity of the worm gear mechanism and even allowing for replacement of the nut 37 a if needed.

FIGS. 26 to 30 show a further improvement on the preceding embodiment in compactness of configuration of the system where the fan and motor housing 47 is smaller and more rectangular in plan. This also includes a tapered outlet duct 48 for the air extraction that has a rim 49 to slot mount into a groove 50 of the fan and motor housing 47 at a point just outboard of the one way airflow flap valve 21″. The lid 46 for the housing is stepped downwardly over the air outlet area.

Referring to FIGS. 31 and 32, these illustrate, respectively, the flushing action and the air suction action of the system.

FIG. 33 shows refinements to the lower end 33 of the air extraction pipe comprising: a reduction in size of the lateral apertures 34 and provision of vertically extending ribs 60 on the internal surface of the pipe wall between the apertures to strengthen the moulding; and provision of a pip 61 on the external surface of frusto-conical wall 30 to locate in a corresponding recess 62 in the co-operating frusto-conical face of the base part 40 for facilitating radial alignment of the two during assembly/installation.

FIG. 34 shows provision of radially spaced apart props 63 to support and act as an appropriate end stop for travel of the lower end of the sleeve 35 a suitable height above the shelf 64 of the base part 40 for optimal contact of the washer 39 with the lip/seat 43. Furthermore an end skirt 65 is now provided on the lower end 33 of the air extraction pipe to fit into a reduced internal diameter portion 66 of the base part 40.

FIG. 35 shows provision of a raised annulus 67 around the outside diameter of the upper air extraction pipe section 32 to facilitate centreing of the sleeve 35 as it telescopes up and down the air extraction pipe. It should be noted that the term “telescope” as used herein refers to the ensheathing sliding arrangement of the tubes and does not refer to one sliding beyond the other.

In addition to or alternative to provision of the annulus 67 the pipe or sleeve may have a groove for an O ring or similar or may have ribs to facilitate the centreing.

Turning now to FIGS. 34 and 35 these show a novel type of overflow valve that may be made more compact and cheaper than the ball valve arrangement of the preceding embodiment. Here the overflow valve has a plug 100 that has a hat portion 70 which is formed to have a centrally flat 71 underside to seat onto the rim of the overflow pipe and with a surrounding annular recess 72 whereby it is arranged to be buoyant, stable and not capsize. The recess 72 serves to trap air for buoyancy and the plug 100 will thus float up if the water level in the cistern should rise beyond normal. A central pillar 74 with four radial vanes extends downwardly from the underside of the plug to help to keep the valve in place over the overflow pipe and avoids the need for a cage unlike the floating ball valve. 

1. A ventilation system for removal of foul air from a toilet bowl, where the toilet is of the flush down type having a cistern storing water for flushing the toilet bowl and with a flushing pipe feeding from the cistern to the toilet bowl for flushing the toilet bowl, the system having an air extractor fan mounted within the cistern and communicating with an air extraction pipe which communicates, in turn, with the flushing pipe whereby the air extractor fan may draw foul air from the lavatory bowl via the flushing pipe and air extraction pipe and expel it through a removal pipe, wherein the air extraction pipe and at least such of the length of flushing pipe that is within and emerges through the cistern are substantially straight and the air extraction pipe is aligned with the flushing pipe and with the air extractor fan whereby air may flow directly in a straight line into and up through the flushing pipe length and the air extraction pipe into the fan for expulsion.
 2. A ventilation system as claimed in claim 1, wherein the system has a flushing mechanism comprising a tubular sleeve that is mounted telescopically to the air extraction pipe and which when moved telescopically opens at least one aperture into the air extraction or flushing pipe for water to flow thereinto from the cistern.
 3. A ventilation system as claimed in claim 2, wherein the tubular sleeve slides concentrically over the air extraction pipe, the inner wall of the tubular sleeve and/or outer wall of the air extraction pipe having one or more spacing lugs, rings or ribs to maintain the concentricity.
 4. A ventilation system as claimed in claim 2, wherein the tubular sleeve carries an annular valve sealing member around its lower, in use, end to seat against a valve seat.
 5. A ventilation system as claimed in claim 4, wherein the valve seat is formed at an upper, in use, end of the flushing pipe length.
 6. A ventilation system as claimed in claim 2, wherein the flushing mechanism is operated by an electric motor that is coupled to the tubular sleeve by a worm gear or other threaded gear.
 7. A ventilation system as claimed in claim 6, wherein the worm gear, or threaded gear comprises a moulded drive nut that is driven by the worm gear or other threaded gear.
 8. A ventilation system as claimed in claim 7, wherein the valve sleeve has a support arm projecting therefrom and having a socket in which the drive nut is inserted in use to drive the valve sleeve.
 9. A ventilation system as claimed in claim 1, wherein the system further has a baffle that comprises a generally frusto-conical barrier that is annular.
 10. A ventilation system as claimed in claim 9, wherein the baffle is mounted in the air extraction pipe in proximity to the air extraction fan to restrict back flow of any moisture from the air extraction pipe to the air extractor fan.
 11. A ventilation system as claimed in claim 1, wherein the system is substantially wholly packaged within a cistern and wherein the electric motor is housed together with the extractor fan within a substantially watertight housing that is installed within the cistern, in use.
 12. A ventilation system as claimed in claim 1, wherein the system further comprises a processor means configured to activate a flushing operation action followed by operation of the extractor fan.
 13. A ventilation system as claimed in claim 1, wherein the system has an electric sensor to sense the presence of a toilet user and to automatically activate operation of the extractor fan and then the flush, as the user moves away, followed by the extractor fan.
 14. A ventilation system for removal of foul air from a toilet bowl, where the toilet is of the flush down type having a cistern storing water for flushing the toilet bowl and with a flushing pipe feeding from the cistern to the toilet bowl for flushing the toilet bowl, the system having an air extractor fan mounted within the cistern and communicating with an air extraction pipe which communicates, in turn, with the flushing pipe whereby the air extractor fan may draw foul air from the lavatory bowl via the flushing pipe and air extraction pipe and expel it through a removal pipe, wherein the system is formed or assembled with a flushing means for flushing of the toilet comprising a tubular sleeve that is mounted telescopically to the air extraction pipe and which when moved telescopically opens at least one aperture into the air extraction or flushing pipe for water to flow thereinto from the cistern.
 15. A ventilation system as claimed in claim 14 further as claimed in any of claims 1 to
 13. 16. A ventilation system as claimed in claim 14 and further having an overflow pipe coupled to the flushing pipe length.
 17. A ventilation system as claimed in claim 16, wherein the overflow pipe has a floating valve that is in the form of a floating plug.
 18. A ventilation system as claimed in claim 17, wherein the floating valve has a head part with an underside to seat onto the upper end of the overflow pipe and where the underside is further adapted to trap air for buoyancy.
 19. A ventilation system as claimed in claim 17, wherein the floating valve has a column projecting from its underside to fit into the upper end of the overflow pipe and retain the plug over the pipe.
 20. A floating valve for a toilet cistern overflow and which is plug-shaped having a head part with an underside to seat onto the upper end of the overflow pipe and where the underside is further adapted to trap air for buoyancy.
 21. A floating valve for a toilet cistern overflow and which is plug-shaped having a column projecting from its underside to fit into the upper end of the overflow pipe and retain the plug over the pipe. 